Understanding the interactions between water and Fe-based clusters is necessary to unravel the micromechanics of the surface hydrophilic property and the corrosion process of iron-related materials. Herein, a theoretical study is conducted of water adsorption and dissociation on icosahedral Fe13 and Fe12X (X = Ti, V, Cr, Mn, Co, Ni) clusters. It is found that the doping atoms have significant influence on the geometric structures, magnetic moments, and electronic states of Fe12X clusters. The center-doped clusters X@Fe12 show higher stability than the shell-doped X-Fe12; Ni@Fe12 exhibits lower activation energy for the dissociation of H2O than all the others; Ti@Fe12 strikes a weak bonding energy and high activation energy for water dissociation. Also, a water dimer finds a decreased energy barrier for O-H dissociation, and the electronic states and metal-water interactions can be altered by the support effect. This information is helpful to those working on water chemistry, anticorrosion wading devices, and high-standard potable water utilization.